Abstract: A method and an installation for recovering energy in the thermal destruction of pollutants in a gas emitted from a scrap preheating device (6,8), e.g. in an electro-steel furnace (1). The polluted gas is conducted through regenerative heat exchangers (12,15) before or after passing through a combustion chamber (4), for providing heat exchange between the polluted cold gas and the cleaned hot gas. The regenerative heat exchangers (12,15) are filled with a packing of a material suitable to be charged into the furnace (1) generating the gases which are used in the scrap preheating process, or into another nearby furnace. The packing is withdrawn completely or partly when the performance of a heat exchanger has deteriorated as a result of oxidation or clogging with dust. A new packing is supplied to the heat exchanger concerned, and the packing withdrawn is charged into one of said furnaces.